65 lines
2.5 KiB
Plaintext
65 lines
2.5 KiB
Plaintext
page.title=Manipulating Broadcast Receivers On Demand
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parent.title=Optimizing Battery Life
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parent.link=index.html
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trainingnavtop=true
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previous.title=Determining and Monitoring the Connectivity Status
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previous.link=connectivity-monitoring.html
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@jd:body
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<div id="tb-wrapper">
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<div id="tb">
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<h2>This lesson teaches you to</h2>
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<ol>
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<li><a href="#ToggleReceivers">Toggle and Cascade State Change Receivers to Improve
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Efficiency</a></li>
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</ol>
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<h2>You should also read</h2>
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<ul>
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<li><a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a>
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</ul>
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</div>
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</div>
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<p>The simplest way to monitor device state changes is to create a {@link
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android.content.BroadcastReceiver} for each state you're monitoring and register each of them in
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your application manifest. Then within each of these receivers you simply reschedule your recurring
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alarms based on the current device state.</p>
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<p>A side-effect of this approach is that your app will wake the device each time any of these
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receivers is triggered—potentially much more frequently than required.</p>
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<p>A better approach is to disable or enable the broadcast receivers at runtime. That way you can
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use the receivers you declared in the manifest as passive alarms that are triggered by system events
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only when necessary.</p>
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<h2 id="ToggleReceivers">Toggle and Cascade State Change Receivers to Improve Efficiency </h2>
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<p>Use can use the {@link android.content.pm.PackageManager} to toggle the enabled state on any
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component defined in the manifest, including whichever broadcast receivers you wish to enable or
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disable as shown in the snippet below:</p>
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<pre>ComponentName receiver = new ComponentName(context, myReceiver.class);
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PackageManager pm = context.getPackageManager();
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pm.setComponentEnabledSetting(receiver,
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PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
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PackageManager.DONT_KILL_APP)</pre>
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<p>Using this technique, if you determine that connectivity has been lost, you can disable all of
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your receivers except the connectivity-change receiver. Conversely, once you are connected you can
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stop listening for connectivity changes and simply check to see if you're online immediately before
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performing an update and rescheduling a recurring update alarm.</p>
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<p>You can use the same technique to delay a download that requires higher bandwidth to complete.
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Simply enable a broadcast receiver that listens for connectivity changes and initiates the
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download only after you are connected to Wi-Fi.</p>
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